Porteus

This works for me.

echo guest | sudo -S activate $OPTIONAL/$CHROME > /dev/null 2>&1 &

The two variables are the folder the module is in and the module file's name.

This works for my file manager.

guest@porteus:~$ echo toor | sudo -S nemo
^C
guest@porteus:~$

On my system, sudo asks for the guest password
echo guest (or whatever the current password is)

Actually, it does on mine also.

guest@porteus:~$ echo guest | sudo -S nemo
Password: ^C
guest@porteus:~$